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WEBENCH® Tools/LM7171: LM7171

NAJEEB QURESHI
Prodigy 60 points
Part Number: LM7171
Other Parts Discussed in Thread: TINA-TI

Tool/software: WEBENCH® Design Tools

Hi,

is there any way to configure LM7171 to get output same as input or less? like there is a input signal 10.7 MHz @ 1.5V.  I need output to be 1.5V to 0.1V using potentiometer. means changing the gain of amplifier output should vary from 1.5V to 0.1V.

  • 0
    Guru 47535 points

    Sure Najeeb, just do an inverting attenuator - also

    It seems the Webench tools pick the LM7171 for a lot of solutions, not the best part necessarily for new designs. List your requirements for a better option. 

  • 0 in reply to Michael Steffes
    Guru 47535 points

    Incidentally Najeeb, I had started an e2e query guidelines template some time back, updated that today - this might help, 

    Suggestions for effective circuit help requests –

    1. Where your question has a specific circuit/device involve, be sure to show the full circuit and more preferably a TINA schematic link. Debug usually involves circling the device pins looking both directions for interactions. What is driving your input – what is your load?
    2. “It doesn’t work” leaves a lot to be desired. Be as specific as possible where your current implementation is falling short of expectations.
    3. Eventually, any design has some target performance metrics. Detailing those will go a long way towards reaching an effective end solution. This might require changing device solutions.
    4. Requirements include,
      1. Eventual output Vpp requirement – that leads into a minimum or preferred set of power supplies – if you know your supplies, report them.
      2. Min/max frequency range – often, DC is the min (if not, AC coupled designs bring in some important design options), but what is the maximum – that with the gain will give you required minimum gain bandwidth product for a VFA solution. Often, you need to provide a lot more margin there than the signal needs if distortion or settling time are of interest. Also, once you have a maximum signal frequency and output Vpp, that wills set a minimum slew rate – and again, if you care about distortion, the device slew rate needs to exceed the signal requirements.
      3. DC precision requirements – usually drift is more important than 25C output error band. Keep in mind the TINA models have a nominal 25C DC error value for each term, but a full worst case needs to consider the device spec limits.
      4. Any noise considerations – if so, report those.

  • 0 in reply to Michael Steffes
    Prodigy 60 points

    Can I have a link to access Webench tools? I am choosing part in TI-TINA and running simulation.

  • 0 in reply to NAJEEB QURESHI
    TI__Genius 15555 points

    Hello Najeeb,

    It would be better to filter down your options using the parametric search and then using the TINA-TI model on the product page of the device. There you can find the most up to date simulation model. For a bandwidth of 10MHZ, you may want to look into a precision device:

    If trying to build an active filter you can use the webench filter designer tool here:

    https://www.ti.com/design-resources/design-tools-simulation/filter-designer.html

    Best,

    Hasan Babiker